The present study was undertaken to develop a rapid, quantitative, in vitro system for evaluating antiviral agents, neutralizing antibodies and various cytokine effects on HIV-1 replication. A system was develop to simultaneously test the effect of various agents on 1) the replication of representative strains of HIV, 2) virus transmitted free of cells or associated with cells,and 3) HIV transmitted to T-cells and monocytes. In conjunction with the NIAID/WHO Antibody Serologic Project (ASP), the assay was used to evaluate the potency and strain specificity of controls and purified monoclonal antibodies (MAbs, 7 human, 7 mouse) directed toward V3, V2 gp41, and CD4 binding regions of HIV-1 gp120. there were 20 labs participating in the ASP study and the novel "LTR-CAT" Target cell assay was among the most sensitive and specific neutralization assays in the study. Results were presented at Neutralization of HIV-1: Technology and regents for analysis of prophylactic vaccines clinical trials meeting April 19-20, 1993 sponsored by FDA and NIAID. Collective ASP-2 study data was analyzed and written for publication (see "Evaluation of monoclonal antibodies to HIV-1 by neutralization and binding assays; An international collaboration" D'Souza, Geyer, Hanson, Hendry and Milman submitted to AIDS Res. & Hum.Ret.). In collaboration with Dr. Beaucage (OTRR/DHP/MPS), the inhibitory effects of modified TAT antisense oligonucleotides are under investigation.